NGuard

Lightweight guard / pre-condition / parameter validation library for .NET

Installation

PM> Install-Package NGuard

Using NGuard

You can use a guard to ensure your method parameters match certain preconditions:

void ExampleMethod(string input)
{
    Guard.Requires(input, nameof(input)).IsNotNull();

    // method body
}

Multiple guards can be chained together:

void ExampleMethod(string input)
{
    Guard.Requires(input, nameof(input)).IsNotNull().IsNotEmpty().IsNotWhiteSpace();

    // method body
}

Defining a custom guard

Custom guards are easy to write. Just create a new extension method:

static Guard<CustomType> SatisfiesCustomCondition(this Guard<CustomType> guard)
{
    if (guard.Value != null)
    {
        bool valid = /* code to test custom condition */
        if (!valid)
        {
            throw new ArgumentException(
                message: $"{guard.Name} should satisfy custom condition.",
                paramName: guard.Name);
        }
    }

	return guard;
}

Now you can use your custom guard:

void ExampleMethod(CustomType value)
{
    Guard.Requires(value).SatisfiesCustomCondition();

    // method body
}

Copyright

Copyright Matthew King 2012-2022.

License

NGuard is licensed under the MIT License. Refer to license.txt for more information.